Size may not matter, but age does - at least for worm mums, as shown by a recent study done in the model organism C. elegans.

Even if genetically identical and living in the same environment (the same Petri dish, even), individuals of this species of worms differ amongst them: some are larger, others live longer, some have more offspring. “We observed that the age of a mother has a major impact on the physiology of her offspring” states Marcos Francisco Perez, PhD student at the CRG and co-first author of this work. “Surprisingly, however it is the youngest mothers that produce offspring that are shorter, grow slower, are less resistant to starvation and have fewer offspring themselves” explains post-doctoral researcher and co-first author of the study, Mirko Francesconi.

These impairments seem to be caused in part because young mothers put less yolk (a specific protein complex) into their eggs. In turn, this is probably because the young mums are smaller. So, why bother to have progeny so early? According to the scientists, producing progeny early in life, even if they are of lower quality, is beneficial because it dramatically shortens the generation time of the species.

“What’s particularly interesting is that the age of an individual’s mother determines their characteristics throughout their lives,” adds Ben Lehner, ICREA Professor and head of the CRG lab where the study took place. “This is a really interesting example of how the physiology of a previous generation can alter not only the development of an animal but also its characteristics as a mature adult” - MM/PRBB